Hydrogen is a valuable product that is used in refining and petrochemicals processing, and methods are needed to increase hydrogen recovery from pressure swing adsorption (PSA) units. This is especially true in regions where hydrogen has a high value and current practice uses added compression power (vacuum regeneration, tail-gas recycle, or two PSAs in series) to increase hydrogen recovery. This invention disclosure proposes an alternative approach that can be applied in refineries and refinery/petrochemical complexes where natural gas is used as fuel. While fuel oil or fuel gas is often used for the fuel requirements of refineries and petrochemical plants, in some cases it is desirable to use natural gas for process and utility heaters and for electricity generation with gas turbines to reduce or eliminate fuel oil generation from the refinery by utilizing bottom of the barrel processing technology.
In the case of the use of natural gas to provide the fuel needed for the operation of the refinery, it has now been found that the natural gas can be used as a co-purge stream in the pressure swing adsorption unit to increase hydrogen recovery. As shown herein, this approach provides economic, safety, and operational/reliability advantages compared to current practices by eliminating a vacuum compressor and thereby reducing compression power requirements.